Analyze 2-D heat transfer of ultrafast laser heated thin films under size effects

Abstract

An improved dual-phase-lagging model which reflects size effects caused by nanostructures is utilized to investigate the 2-D thermal conduction of nanosilicon films irradiated by ultrafast laser. The integral transformation method is used to solve the conduction governing equation based on the improved dual-phase-lagging model. The variation of the internal temperature along the thickness direction and the radial direction of the thin film is analyzed. We find that the temperature increases rapidly in the heated region of the film, and as time goes by, the energy travels from the heated end to another end in a form of wave. Although both the improved dual-phase-lagging model and the dual-phase-lagging model can obtain similar thermal wave temperature fields, the temperature distribution in the film obtained by the improved dual-phase-lagging model is relatively flat, especially for high Knudsen number. Under the same Knudsen number, the temperature obtained by the 2-D improved dual-phase-lagging model is higher than that obtained by the 1-D model, and the temperature difference becomes larger and larger as time elapses.